Time-resolved laser-induced fluorescence spectroscopy as a diagnostic instrument in head and neck carcinoma

Objective: The objectives of this study were to 1) determine differences in lifetime fluorescence between normal and malignant tissue of the upper aerodigestive tract, and 2) evaluate the potential of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) as a diagnostic instrument for head and neck squamous cell carcinoma (HNSCC). Study Design: Cross-sectional study. Setting: University-based medical center. Subjects and Methods: Nine patients with suspected HNSCC were included. In the operating room, a nitrogen pulse laser (337 nm, 700-picosecond pulse width) was used to induce tissue autofluorescence of normal tissue and suspected malignant lesions. Spectral intensities and time-domain measurements were obtained and compared with the histopathology at each site. A total of 53 sites were measured. The fluorescence parameters that provided the most discrimination were determined. Results: Differences in spectral intensities allowed for discrimination between malignant and normal tissue. The spectral intensity of malignant tissue was lower than that of normal tissue, and a shift of peak intensity to a longer wavelength was observed in the normalized spectrum of malignant tissue in the range of 360 to approximately 660 nm. Multiple time-resolved fluorescence parameters provided the best diagnostic discrimination between normal tissue and carcinoma, including average lifetimes (i.e., at 390 nm: 1.7 ± 0.06 ns [not significant] for normal and 1.3 ± 0.06 ns for tumor, P = 0.0025) and the second-order Laguerre expansion coefficient (LEC-2) (i.e., at 460 nm: 0.135 ± 0.001 for normal and 0.155 ± 0.007 for tumor, P < 0.05). Conclusion: These findings highlight some of the differences in lifetime fluorescence between normal and malignant tissue. TR-LIFS has potential as a noninvasive diagnostic technique for HNSCC.